The present invention relates to circuitry which will provide pulses to a sequence of separate conductors in such a manner that the pulse on a second conductor is spaced timewise from a pulse on a first conductor by a predetermined interval and a pulse on a third conductor is spaced timewise from the pulse delivered to the second conductor by the same predetermined interval, and so on throughout the sequence of conductors.
More particularly the invention relates to circuitry for sequentially discharging respective ones of a plurality of condensers to respective ones of a plurality of conductors at precisely separated time intervals. Such circuitry has particular advantages in blasting machines wherein the sequence of conductors are connected to respective explosive charges, and the individual conductors of the sequence are energized at precisely spaced apart time intervals.
An object of the present invention is the provision of new and improved circuitry of the above described type comprising: two or more electronic control switches connected to respective conductors to deliver electrical energy thereto, signal generating means of a type which bleeds a regulated voltage through selectable resistors to an electronic switch having a threshold control voltage for turning itself "on" to generate spaced apart pulses, and pulse transmitting circuitry which will actuate sequential ones of said electronic control switches by sequential ones of said spaced apart pulses.
Another object of the invention is the provision of new and improved circuitry of the above described type in which the sequential pulses are blocked from reaching any particular one of the control switches until the immediately preceding control switch has been actuated by one of the pulses. Another object of the invention is the provision of new and improved circuitry of the immediately above described type wherein a "lockout" switch is provided which prevents all pulses from being delivered by the pulse generator until a predetermined constant voltage is applied to the electronic control switches that in turn supply energy to the load (blasting cap) conductors.
Another object of the invention is the provision of a new and improved power supply for assuring a constant voltage to the load circuitry and which comprises a transformer having a center tapped control winding, a semi-conductor requiring a predetermined voltage on the output of the transformer before passing a current, and a switch controlled by the semi-conductor and which is arranged to remove the bias to the control winding when the switch is energized.
Another object of the invention is a voltage control circuitry of the immediately above described type in which a signal from the voltage control switch actuates another switch which grounds out and disables the biasing circuitry of the lockout switch of the pulse generator which prior thereto had shut off the output of the pulse generator.
A further object of the invention is the provision of a "charge" switch which normally shorts out the charging circuit to load condensers until the charge switch is actuated.
A further object is the provision of a "fire" switch which normally shorts out the conductors from the load condensers, and also disconnects the pulse generator from the control switches, until the fire switch is actuated.